Three years ago I wrote the article Building a multi-room networked home audio solution for FREE, Part 1 and never wrote part 2, where I promised I would show everyone how to put together a professional grade system for around $1,000. To date part 1 has been the most popular home network article on this site with over 45,000 views (next to the random article I wrote on how to remove a broken dipstick, which has over 73,000 views).

Media Mall Sound Cards & Media Devices Driver Download 64-bit
Mediamall Sound Cards & Media Devices Driver Download

A few things have changed in those 3 years, inflation happens you know, but prices are still close to the same. There are more options now however, which I'll highlight as we go. My home has an accessible crawlspace which made running speaker wire insanely easy. Without that you may need to get creative, this article is going to assume you have the ability to at least run a little wire.
Here's a breakdown of what we will need:

You generally want a sound card with signal-to-noise ratio over 100dB, but the best sound cards are in the 124dB range, which is a significant improvement. Channels - A lot of decent, budget-friendly sound cards typically support 5.1 channel audio, but you can spend a little more to get one that can handle 7.1 surround sound. CVC.Medial Sounds. Word Work Activity Cards (or Center) There are 100+ Activity Cards where the medial sound is missing in a CVC word card with a picture. Drivers intel motherboards. Children pick letter tiles, magnetic letters, or write with dry erase marker to fill in the missing initial sound space on their card.

Whole house multi-channel amplifier
At least one Logitech media player, more for multiple independent zones
A Logitech Media Server (many NASes include this, an old PC running Vortexbox is another great solution)
In-wall speakers
In-wall speaker wire
Subwoofer
Lossless music format such as FLAC or ALAC
Optional: In-wall volume control

And really that's it.

The amp
Let's talk about the amp first. Back when I put the system together I went with the Dayton Audio MA1240a Multi-Zone 12 Channel amplifier, which retails for $444 at press time. The sound is very crisp and clear, no distortion and this amp is very customizable. True audiophiles will snub their noses at the Dayton Audio amp, but I can say I have a Pioneer SC-63 amp on some beautiful old Polk Audio SDA-2Bs and the sound quality rivals that combination. Of course, this amp is rated at 40W per channel, so it doesn't get as loud as the SC-63, but for whole house listening it's PLENTY LOUD.
But before we go in to why this amp is good, let me mention there is now a 65W per channel version of the amp, the Dayton Audio MA1260 Multi-Zone 12 Channel amplifier. Essentialy the same specs with more power, for $100 more. Your choice, pick your poison, I'm not sure I would go for the more powerful amp for $105 more given how loud this amp is while still remaining crystal clear.
Anyway, why this amp? First of all, the sound is crisp and clear and the price is right. On top of that with 12 channels you get six zones, which is perfect for whole house audio. But the magic doesn't stop there, let's take a look at the back of the amp.
The amp is almost infinitely customizable, which you really want when setting up whole house audio. The amp can be triggered to turn on, it also auto sleeps well so it won't sit there using phantom power.
It also has two sets of main inputs and two sets of main outputs. Additionally each zone has its own Line In, and input selection can be individually set to each speaker in the zone. Let's breakdown what this actually means. Let's say to start out you just want to use one media player, heck let's say you just want to use the Logitech Media Player that comes with the Vortexbox. In this scenario you use the #1 Bus Input and set all of your zones to Bus 1, boom, audio through your whole house from one player.
But down the road let's say you don't want the patio playing music all the time while the house is playing music. With this scenario you add a player to that zone, use the Zone-specific Line In and then set the Zone Bus selection to Line In. Or you could plug in to Bus Input 2 and have multiple zones using that player. You don't have to be the player either, you can use one of the player solutions I mentioned in Part 1 or even just a Raspberry Pi running Squeezeslave.
The amp also has per channel gain control, so say your kitchen speakers are louder than the rest of the house, just fine-tune that zone. The Dayton Audio amp packs a whollup for the price and in my 3+ years of use I've been extremely happy with it.
The Player

This solution is based on Logitech's Squeezebox line of players, but really it can be customized as desired if you have a better solution. If the plan is to start with just one player I'd recommend getting a Squeezebox Duet simply because you get the player AND the remote for around $100 on ebay if you are picky and can wait for a good deal. Check here for an ebay search of the Logitech Squeezebox Duet.
If you don't want to spend the money on a player there are other options. You can simply load SqueezePlay on to a computer and use it as the player (you'll need to get the audio in to the amp). Or you can simply use the VortexPlayer on the Vortexbox, which we'll get to below. You don't get the official remote with these solutions, but Squeezebox remotes are readily available on iOS and Android. Only official solutions get free Pandora as well, with an open source player you need a Premium Pandora membership, but that's not a huge deal.
The Media Server

To run the solution I'm describing you need a Logitech Media Server. That's not as scary as it sounds. Most NASes these days come with a Logitech Media Server package. If you have a NAS explore that option, it will probably work well for you. If that's not an option you can always download Logitech Media Server run it on a Windows PC, Mac or Linux PC. Lastly, my favorite option is the Vortexbox. The Vortexbox let's you rip movies, rip music and store and play them all, amongst many other things. Best of all it can be run on an ancient PC. I've 'upgraded' mine to a Dell Zino HD. Literally the only thing that should cost you money for the media server step is maybe buying a large hard drive space if you go crazy ripping to FLAC or ripping movies. The Dell Zino cost me $68 on ebay, but before that I had it Vortexbox running on my old computer from 2002.
As a bonus the Vortexbox comes with its own Logitech Squeezebox player, so you can simply plug the old computers sound card in to the amp. I can't guarantee the best sound if you do this, but it's an option.
The Speakers

If there's anything you need to put though in to it's the speakers. Parts Express does have a great selection of in-wall and ceiling speakers, but that wasn't an area that I wanted to experiment with. I went to Newegg.com and picked out some Polk Audio RC55i 5.5' two-way speakers. Back then I paid under $100 per pair. Crutchfield now has the Polk Audio RC55i for $129.99 per pair. I also got a set of 8' Polk Audio RC85i in-wall two-ways for the bedroom for $169. I went the larger speakers in the bedroom since I wasn't going to have a subwoofer in there and didn't want tinny sound. I debated different manufacturers such as Klipsch, or even higher model Polk Audios, but ended up with these and have been happy with them. Depending on what you choose for speaker configuration, this category can eat up your budget fast.
Let's talk speaker placement. When you think of whole house audio you often think of ceiling speakers or speakers high in the wall. This is ok for background music speakers, but if you want really good sounding music that you can sit and listen to, consider speaker placement carefully. In my home I have several speakers high in the wall, but my main listening speakers face the couch on either side. This sounds amazing when I'm sitting just listening to music. When I first set them up they were off to the side, you don't want to do this. They sounded good for background music, but awful for sitting and listening.
The subwoofer

With the 5.5' two-way in-wall speakers you aren't going to get incredible bass. You can spend a shitload on a subwoofer, but since I had been so happy with the Dayton Audio amp, I decided to give the Dayton Audio SUB-1000 10' 100 Watt subwoofer a chance. I am so glad I did

Mediamall Sound Cards & Media Devices Driver Download